Tea polysaccharides (TPS) are regarded as some of the main bioactive constituents of tea made from the leaves and buds of the tea plant (Camellia sinensis L.). An increasing number of studies have demonstrated that TPS can reduce the risk of type 2 diabetes, obesity, and other metabolic diseases. However, the potential mechanisms responsible for antidiabetic and antiobesogenic activities of TPS remain unclear. Therefore, the cellular and physiological mechanisms that underlie the antidiabetic and antiobesogenic effects, including antioxidant and anti-inflammation effects, inhibition of digestive enzymes, prevention of macronutrient absorption, and expression of gene and protein, were summarized in this review. Furthermore, the gastrointestinal functions of TPS and the role of gut microbiota in the prevention and treatment of metabolic diseases were discussed. It is expected that the present review will be helpful for enhancing our knowledge about the health-promoting effects of TPS on metabolic diseases and stimulating further works on TPS.

No abstract

A highly enantioselective catalytic asymmetric (4 + 1) annulation reaction of nitroalkenes and ammonium ylides is reported for the first time.

No abstract

A domino cyclization of oxime esters and imines has been achieved by dual photoredox/ copper catalysis. A variety of structurally diverse fully substituted dihydropyrimidines have been forged in 37-88% yields at room temperature. This synthetic protocol provides N-heterocycles with high molecular complexity and functional group diversity. The present reaction is amenable to gramscale synthesis, which is expected to find potential applications in organic synthesis and drug discovery. A plausible reaction mechanism is proposed.